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23 Cards in this Set
- Front
- Back
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What four microbes are "the enemy"?
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Viruses, bacteria, fungi, and parasites
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What are the top three causes of death in the world?
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1. Cardiovascular disease
2. Infectious Disease 3. Cancer |
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What type of infection is the number one killer?
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Lower respiratory infection, including pneumonia
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Describe the composition of a virus. Are they living?
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A virus is a nucleic acid (DNA or RNA) surrounded by a protein coat. The protein coat is a capsid. Some viruses have a lipid membrane surrounding the capsid, called the envelope. Feldman believes viruses are not living, because they can't make proteins, generate energy, or have ionic potential across their membranes
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Which viruses are more stable - enveloped or non enveloped? Why? How do the different viruses tend to be transmitted?
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Non-enveloped viruses are more stable than enveloped viruses. This is because the lipid membrane is very vulnerable, especially to alcohols, detergents. The membrane contains viral glycoproteins which are necessary for infection, so when these are lost the virus is no longer infectious.
Transmission of non-enveloped viruses is usually through the fecal - oral route, since they can survive in the GI tract. Transmission of enveloped viruses is usually from person to person, animal to person, or animal to vector to person |
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Why is it hard to find treatments for viruses? What are some viral treatments?
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It is hard to find viral targets, because they share so many functions with us (killing the virus would kill us too). Some viral drugs are toxic to us for this reason.
AZT and protease inhibitors are treatments for HIV |
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What are some properties of bacteria?
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They have no nucleus, they have one circular chromsome, they have a complex cell wall, which we lack.
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Is the ribosome used by bacteria the same that we use? How do the division of bacteria compared to the divison of human cells?
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No, bacteria use a 70s ribosome and we use an 80s ribosome. Bacteria divide in 20 min or more, human cells take 24 hours to divide
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What are the differences between gram negative and gram positive bacteria?
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Gram positive bacteria have two layers, and a thick peptidoglycan layer. They stain purple
Gram negative bacteria have three layers, including an outer membrane, and they have a thin peptidoglycan layer. They stain red |
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What is the purple stain in Gram staining? The red stain?
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The purple stain is crystal violet. The red stain is safranin red
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How does the Gram stain work? Why do gram positive bacteria stain purple and gram negative stain red?
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In the grams stain, you first stain with crystal violet. You then wash out the stain with alcohol. You then stain it with safranin red.
Gram positive bacteria have a thick peptidoglycan layer, which retains the purple crystal violet stain despite being washed. The gram negative bacteria have a thin peptidoglycan layer, so they lose the crystal violet and show the safranin red stain |
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What structures are found on the outer membrane of the gram negative cells?
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Porins and LPS.
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What part of the bacteria is targeted in treatment? What difficulty is encountered when treating gram negative bacteria?
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The cell wall is targeted. Their lipid membrane prevents drugs from reaching the cell wall, unless they can pass through the porins.
Protein synthesis is also targeted, since bacteria use a different ribosome then we do The circular bacterial DNA is also targeted, since they se helicases and gyrases that we don't |
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When a pathogen enters the body, does the innate or adaptive immune system respond first?
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The innate immune system responds first
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What are the components of the innate immune system.
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1. Toll like receptors
2. Cytokines - inflammation, activation of cells 3. Barriers to infection (skin) and lysozyme in tears 4. Inflammation - slows down growth of pathogen |
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What three components make up the adaptive immune system?
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1. CD8 cells which kill viral infected cells (cytotoxic t cells)
2. CD4 TH2 cells activate B cells to become plasma cells that secrete antibodies 3. CD4 TH1 cells activate macrophages and NK cells that elicit a cellular response against intracellular bacteria and fungi |
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What are the ancient molecules found on pathogens? What are these molecules sometimes caled? What are toll-like receptors? How are these related? Give an example, using LPS
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The ancient molecules are characteristic molecules on pathogens that can be recognized by toll-like receptors. They are sometimes called Pathogen Associated Molecular Patterns (PAMPs). Toll-like receptors are receptors found on scavenger cells like macrophages. They detect the ancient molecules, and sense what type of cell the pathogen is.
For example, gram negative bacteria contain the molecule LPS on their surface. LPS binds the toll-like receptor, which tells the scavenger cell that it found a gram negative bacteria (although it doesn't know which kind). In response, it makes cytokines which generate an immune response specifically for gram negative cells |
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Are there toll like receptors in the cell too? What do they detect, and then do?
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Yes, there are toll like receptors in endosomes. They detect foreign nucleic acid in the cell. They then start a signal transduction to kill the specific types of pathogens.
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Describe which cells have high levels of TLR, medium, and low
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High - macrophages, neutrophils
Medium - dendritic cells, NK cells Low - B cells, T cells |
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What is a PAMP found on gram positive bacterial cells?
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Teichoic acid
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What is the result of the activation of TLRs?
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The secretion of cytokines, which promote the innate immune response, including the inflammatory response
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What are the three arms of the complement system? What do they lead to?
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The classical, the MB Lectin pathway, and the alternative pathway? They lead to the formation of C3, which is used to make a C3a and C5a, which attracts neutrophils. C3b results
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What is opsonization?
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When a molecule or protein completely surrounds a bacteria, leading to engulfment by a macrophage, or lysis by complements MAC
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